Codezwiz >> Forums >> General PHP Nuke Help >> Date comparrison function problems for calendar

Ok, I'm writing a function to determine if a submitted calendar date is already entered into a database, or if a time range is within a time range already entereed in the database.

The time is setup as the typical 2005-12-02 23:00:00 24 hour time format. I need to be able to take 2 dates and compare if one date is before or after the other date. I obviously can't just use the < > operators since these are strings and not plain numbers. I believe that I can use the function strtotime on the dates to convert them to a timestamp, which is then just a big number, which can then be simply compared using math operators. If I use strtotime($time), with $time being a time string like the one I listed above, will that simply convert the time listed into a numerical string related to the Unix epoch? If I do that to both $time and a new time $newtime, can I then just compare them with < > = and be assured that it will work?

Also, say I have a duration of hours and minutes that I need to add to both of these variables to get when the event ended (so it starts at 12 oclock and ends at 2 oclock...so 2 hours added), can I use strtotime to relate this new time? I believe you do that by doing something like strtotime( + $durationhours hours, $time) which is essentially saying "use $time as your base, then add the variable $durationhours number of hours onto this, then return as a unix timestamp"....is this correct? Do I need "" marks or '' anywhere around the variables or the plain text elements in the strtotime function? I tried reading up on this but it's sort of confusing. I think I'm right, but I keep getting errors when I try this out in my script.

Originally posted by harknell @ Fri Dec 02, 2005 11:32 am:

Ok, I'm writing a function to determine if a submitted calendar date is already entered into a database, or if a time range is within a time range already entereed in the database.

The time is setup as the typical 2005-12-02 23:00:00 24 hour time format. I need to be able to take 2 dates and compare if one date is before or after the other date. I obviously can't just use the < > operators since these are strings and not plain numbers. I believe that I can use the function strtotime on the dates to convert them to a timestamp, which is then just a big number, which can then be simply compared using math operators. If I use strtotime($time), with $time being a time string like the one I listed above, will that simply convert the time listed into a numerical string related to the Unix epoch? If I do that to both $time and a new time $newtime, can I then just compare them with < > = and be assured that it will work?

Also, say I have a duration of hours and minutes that I need to add to both of these variables to get when the event ended (so it starts at 12 oclock and ends at 2 oclock...so 2 hours added), can I use strtotime to relate this new time? I believe you do that by doing something like strtotime( + $durationhours hours, $time) which is essentially saying "use $time as your base, then add the variable $durationhours number of hours onto this, then return as a unix timestamp"....is this correct? Do I need "" marks or '' anywhere around the variables or the plain text elements in the strtotime function? I tried reading up on this but it's sort of confusing. I think I'm right, but I keep getting errors when I try this out in my script.

Yes and Yes. What errors do you receive?

Luckily I've made it past this point. The errors I was getting referred to the fact that I was using 24 hour time, but because it was based on a "human" model of showing it (1-24), it caused a strtotime error since strtotime wants a computer 24 hour time (0-23) input. So midnight was blowing up. and since that's the "default" for display I couldn't figure out why the problems were occuring.